Experimental investigation on phase transformation of Cu–Ni–Si alloy melts during cooling

Abstract

Rapid water quenching experiments were first carried out according to differential scanning calorimetry results, and then the microstructure and phase composition of such water quenching Cu–8·33Ni–1·67Si (wt-) samples were investigated. Subsequently, calculation on the competition nucleation of the primary phase was also carried out. Based on the experimental and calculational results, the phase transformation behaviour of Cu–8·33Ni–1·67Si melts during the cooling process was discussed, and the results can be summarised as follows. First, the α-Cu phase formed as a primary phase due to the shorter incubation time and higher time dependent nucleation rate. Subsequently, a eutectic reaction occurred in the interdendritic residual liquid phase of the primary α-Cu grains, and its product was α-Cu+Ni3Si. The third and fourth phase transformation could be described to the precipitation of the δ-Ni2Si phase in the region close to the grain boundary phase and the internal of the primary α-Cu grains respectively.

Characterizations on Precipitations in the Cu-Rich Corner of Cu-Ni-Al Ternary Phase Diagram

“…Although the entire ternary phase diagram of the Cu-Ni-Al system is not obtained, the formation sequence of Ni-Al intermetallics in the Cu-Ni-Al alloying melt during the cooling process can be approximately deduced from the as-cast and heat-treated microstructure along with our previous work on the similar Cu-Ni-Si system [12,19], viz. NiAl phase is the product of solidification, while Ni 3 Al phase precipitates from the aging treatment.…”